test(signal): remove flaky unit test

The signal handler unit test registers the signal handlers, spins up a
new thread, and sends signals to itself (using kill) to check that the
metrics get updated. This is a very complicated test for a unit test,
and it's already covered in the integration test test_signals.py.
As this test is seldomly failing in our CI, it's best to get rid of its
complexity and rely on the integration tests, which are better suited
for this kind of test.

Signed-off-by: Riccardo Mancini <mancio@amazon.com>

Author: Manciukic

src/vmm/src/signal_handler.rs

@@ -50,7 +50,6 @@ macro_rules! generate_handler {
 
             $body(si_code, info);
 
-            #[cfg(not(test))]
             match si_signo {
                 $signal_name => exit_with_code(crate::FcExitCode::$exit_code),
                 _ => exit_with_code(FcExitCode::UnexpectedError),
@@ -170,74 +169,3 @@ pub fn register_signal_handlers() -> vmm_sys_util::errno::Result<()> {
     register_signal_handler(SIGILL, sigill_handler)?;
     Ok(())
 }
-
-#[cfg(test)]
-mod tests {
-    #![allow(clippy::undocumented_unsafe_blocks)]
-    use std::{process, thread};
-
-    use libc::syscall;
-
-    use super::*;
-
-    #[test]
-    fn test_signal_handler() {
-        let child = thread::spawn(move || {
-            register_signal_handlers().unwrap();
-
-            // Call the forbidden `SYS_mkdirat`.
-            unsafe { libc::syscall(libc::SYS_mkdirat, "/foo/bar\0") };
-
-            // Call SIGBUS signal handler.
-            assert_eq!(METRICS.signals.sigbus.fetch(), 0);
-            unsafe {
-                syscall(libc::SYS_kill, process::id(), SIGBUS);
-            }
-
-            // Call SIGSEGV signal handler.
-            assert_eq!(METRICS.signals.sigsegv.fetch(), 0);
-            unsafe {
-                syscall(libc::SYS_kill, process::id(), SIGSEGV);
-            }
-
-            // Call SIGXFSZ signal handler.
-            assert_eq!(METRICS.signals.sigxfsz.fetch(), 0);
-            unsafe {
-                syscall(libc::SYS_kill, process::id(), SIGXFSZ);
-            }
-
-            // Call SIGXCPU signal handler.
-            assert_eq!(METRICS.signals.sigxcpu.fetch(), 0);
-            unsafe {
-                syscall(libc::SYS_kill, process::id(), SIGXCPU);
-            }
-
-            // Call SIGPIPE signal handler.
-            assert_eq!(METRICS.signals.sigpipe.count(), 0);
-            unsafe {
-                syscall(libc::SYS_kill, process::id(), SIGPIPE);
-            }
-
-            // Call SIGHUP signal handler.
-            assert_eq!(METRICS.signals.sighup.fetch(), 0);
-            unsafe {
-                syscall(libc::SYS_kill, process::id(), SIGHUP);
-            }
-
-            // Call SIGILL signal handler.
-            assert_eq!(METRICS.signals.sigill.fetch(), 0);
-            unsafe {
-                syscall(libc::SYS_kill, process::id(), SIGILL);
-            }
-        });
-        child.join().unwrap();
-
-        assert!(METRICS.signals.sigbus.fetch() >= 1);
-        assert!(METRICS.signals.sigsegv.fetch() >= 1);
-        assert!(METRICS.signals.sigxfsz.fetch() >= 1);
-        assert!(METRICS.signals.sigxcpu.fetch() >= 1);
-        assert!(METRICS.signals.sigpipe.count() >= 1);
-        assert!(METRICS.signals.sighup.fetch() >= 1);
-        assert!(METRICS.signals.sigill.fetch() >= 1);
-    }
-}